Occlusion cannula and methods of use

ABSTRACT

The invention provides a nested tubing cannula which comprises outer and inner elongate tubular members, each having a proximal end, a distal end, and a lumen therebetween. The inner tubular member is sealed at its distal end and is nested substantially coaxially within the lumen of the outer tubular member, so that the gap between the inner and the outer tubular member defines a second lumen whereas the first lumen is the lumen of the inner tubular member. A tubular sleeve is disposed coaxially between the inner and outer tubular members. A balloon is mounted on a distal region of the outer tubular member and is in communication with the first lumen. The cannula further comprises a port proximal or distal the balloon occluder and is in communication with the second lumen. Methods for making the devices herein are disclosed.

[0001] This is a continuation of co-pending U.S. patent application Ser.No. 09/531,726, filed Mar. 21, 2000, which is a continuation of U.S.patent application Ser. No. 09/198,439, filed Nov. 24, 1998, now U.S.Pat. No. 6,056,720, all of which are incorporated herein by reference intheir entireties.

FIELD OF THE INVENTION

[0002] This invention relates to methods and apparatus for administeringcardioplegia to the aorta during cardiac surgery. The devices include anocclusion cannula that can include various features such as a cuttingblade, a blade guard, a flange, radiopaque markers and an occluderaligner to properly position the distal end of the device within theaorta. Once the occlusion cannula is in its proper position, theoccluder is expanded to occlude the aorta downstream of the infusionport and cardioplegia solution is then introduced through the infusionport to arrest the heart. The infusion port can alternately be used toaspirate cardioplegia or embolic debris or other unwanted material fromthe aorta.

BACKGROUND OF THE INVENTION

[0003] Currently, the most common method of temporarily occluding theascending aorta and arresting the heart during open-heart surgeryutilizes a mechanical cross clamp and a cardioplegia cannula. Once thechest cavity has been opened, access to the heart and to the adjacentvessels is provided. The ascending aorta is partially dissected from thesurrounding tissue and exposed. Arterial and venous cannulas areinserted and sutured into place. The cannulas are connected to thecardiopulmonary bypass machine, and bypass blood oxygenation isestablished.

[0004] At this point, the heart must be arrested and isolated from therest of the circulatory system. A mechanical cross clamp is positionedbetween the cardioplegia cannula and the aortic cannula and is actuated.The aorta is completely collapsed at the clamp site, thus stopping flowof blood between the coronary arteries and the innominate artery, andthe oxygenated bypass blood is shunted around the heart. Once the vesselocclusion has been completed, cardioplegia solution is introducedthrough the cardioplegia cannula to arrest the heart. The surgeon maynow proceed with the desired operation.

[0005] Other less common means of occluding the aorta includepercutaneous balloon catheter occlusion, direct aortic balloon catheter(Foley) occlusion, aortic balloon catheter occlusion, and an inflatingdiaphragm occluder (Hill—occlusion trocar). The percutaneous ballooncatheter is inserted typically from the femoral artery feed through thedescending aorta, across the aortic arch into position in the ascendingaorta. Once in the ascending aorta, the balloon occluder is inflated andflow stopped.

[0006] As a simple replacement for the mechanical cross clamp, a Foleycatheter may be placed through an additional incision site near thestandard cross clamp site. Once inserted, the Foley catheter balloon isinflated and flow is stopped. Similarly, an aortic balloon catheter isplaced directly into the aorta. This catheter replaces the standardaortic cannula by delivering the cardiopulmonary bypass (CPB) blood backto the arterial circulatory system. The occluder balloon is located onthe catheter proximal to CPB blood exit port on the cannula. Theocclusion trocar is desired to offer similar features as the aorticballoon occluder cannula and would be used in place of the standardaortic cannula. However, it relies on an inflatable diaphragm to occludethe vessel.

[0007] The use of a balloon to occlude an artery has been disclosed byGabbay, U.S. Pat. No. 5,330,451 (this and all other references citedherein are expressly incorporated by reference as if fully set forth intheir entirety herein). The Gabbay device included a perfusion cannulahaving a proximal balloon occluder and a distal intra-aortic balloon todivert blood to the carotid arteries. The Gabbay perfusion cannula isdisclosed for use during open-heart surgery in order to preventcomplications associated therewith.

[0008] Moreover, Peters, U.S. Pat. No. 5,433,700, discusses a method forinducing cardioplegic arrest using an arterial balloon catheter toocclude the ascending aorta. The Peters method includes the steps ofmaintaining systemic circulation using peripheral cardiopulmonarybypass, venting the left side of the heart, and introducing acardioplegic agent into the coronary circulation. This procedure is saidto prepare the heart for a variety of surgical procedures. Disclosuresof similar endovascular occlusion catheters can be found in Machold etal., U.S. Pat. No. 5,458,574, Stevens, International Application No.PCT/US93/12323, Stevens et al., International Application No.PCT/US94/12986, Nasu, U.S. Pat. No. 5,425,708 and Grinfeld et al., U.S.Pat. No. 5,312,344.

[0009] Each of the existing methods of blocking aortic blood flow andarresting the heart carries with it some undesired aspects. Themechanical cross clamp offers simplicity and reliably consistentoperation. However, the physical clamping action on the vessel has beenlinked to many adverse body responses. Barbut et al. (“Cerebral EmboliDetected During Bypass Surgery Are Associated With Clamp Removal,”Stroke, 25(12):2398-2402 (1994), incorporated herein by reference in itsentirety) noted the majority of embolic events (release) is associatedwith the actuation and release of the cross clamp during coronary bypassgraft surgery. The clamping action may be responsible for breaking upand freeing atherosclerotic buildup on the vessel walls. In addition,the potential for vascular damage, like aortic dissections, may alsoincur during the clamp application.

[0010] The percutaneous balloon catheter occluder has a distinctdrawback in that it must be placed with visionary assistance.Fluoroscopy is typically used to position the device in the aorta. Thisadded equipment is not always readily available in the surgical suite.In addition, the catheter placement up to the aorta may also createadditional vascular trauma and emboli generation.

[0011] The use of a Foley catheter to occlude the aorta requires anadditional incision site to place the device. The extra cut is anadditional insult site and requires sutures to close. Generation ofemboli and the potential of aortic dissection directly associated withjust the incision may potentially outweigh the benefits of using thecatheter.

[0012] The aortic balloon occluder cannula addresses many of thedeficiencies of the previous devices. Placement is easy to visualize, noextra cuts are required, and there is no need for the potentiallytraumatic cross clamp. However the currently-available aortic balloonoccluders suffer from problems of migration within the ascending aortabecause the cannulas on which the balloons are mounted are typicallyflexible tubes as disclosed by Grinfeld et al. and Nasu. Attempts tosolve the migration problem include balloon designs with a large“footprint” in the distal region of the cannula. (See Nasu, supra.) Thislarge footprint balloon is a less than adequate solution because itencroaches into the already limited area of the ascending aorta in whichsurgical access is available. Further, use of each of these aorticoccluding balloons requires a cardioplegia cannula to be insertedthrough an additional incision site to arrest the heart.

[0013] A need exists for an aortic cannula having both a balloonoccluder which can isolate the ascending aorta from peripheralvasculature without substantial migration of the occluder into theascending aorta, thereby reducing or eliminating the need for aorticcross-clamping, and an associated cardioplegia infusion port whicheliminates the need for a separate incision for a cardioplegia cannula.Existing devices are inadequate for this purpose.

SUMMARY OF THE INVENTION

[0014] The present invention relates to medical devices and theirmethods of use, and particularly occlusion cannula. The occlusioncannula comprises a cannula having an occluder to isolate the ascendingaorta from peripheral vasculature during cardiac surgery and an infusionport for administering cardioplegia to arrest the heart. The infusionport can alternately be used to aspirate cardioplegia or embolic debrisor other unwanted material from the aorta. The devices of the presentinvention may include various features such as a cutting blade, a bladeguard, a flange, radiopaque markers and an occluder aligner to properlyposition the distal end of the device within the aorta.

[0015] In one embodiment, the device includes a substantially rigidcannula adapted to enter the aorta with a proximal end that receivescardioplegia solution into a cardioplegia lumen and delivers it to aninfusion port in the distal region of the cannula. An occluder, mountedon the distal region of the cannula, expands away from the cannula uponactivation to substantially occlude the aorta downstream from theinfusion port. During use, the occluder isolates the ascending aortafrom the peripheral vasculature. The substantially rigid nature of thecannula inhibits migration of the occluder into the ascending aorta,thus overcoming problems associated with other currently availableaortic balloon cannulas.

[0016] An alternative embodiment of an occlusion cannula may comprise arigid, preformed elongate tubular member having a proximal end, a distalregion, a distal end, and a lumen extending from the proximal end to aperfusion port in the distal region. This lumen and port can be used todeliver cardioplegia. The distal region includes three segments. Thefirst segment is angled from the axis of the proximal tubular member.The second segment curves in a direction opposite from the firstsegment. The third segment is substantially linear and lies atapproximately a 90-degree angle to the axis of the proximal tubularmember. The curved second segment has two beneficial properties. First,it inhibits migration of the occluder into the ascending aorta. Second,the curved segment brings the balloon into closer proximity to theproximal tubular member, and thereby improves stability of the occluderin use. In certain embodiments, the tubular member includes anotherlumen which extends distally and communicates with a port adjacent thedistal region for measuring blood pressure.

[0017] In certain embodiments, the occluder is an inflatable balloon. Inother embodiments, the occluder is a foam-filled, self-expandingballoon. Certain balloon embodiments also include a lumen which can beused to inflate the balloon or alternately can be used to apply negativepressure to deflate the balloon. Other embodiments include an aspirationlumen which terminates at the infusion port so that the infusion portcan alternately be used to deliver cardioplegia solution or aspirateembolic debris and other unwanted material from the aorta. Anotherembodiment further includes an occluder aligner to help position thedistal end of the cannula within the aorta and to stabilize the positionof the occluder during expansion. In another embodiment, the deviceincludes a cannula associated with a cutting blade which is adapted tocut through the wall of the aorta to allow introduction of the cannula.The proximal end of the cannula is adapted to receive cardioplegiasolution into a cardioplegia lumen and deliver it to an infusion port inthe distal region of the cannula. An occluder mounted on the distalregion of the cannula expands away from the cannula upon activation tosubstantially occlude the aorta downstream from the infusion port.During use, the occluder isolates the ascending aorta from theperipheral vasculature. Certain embodiments also include a blade guardwhich moves when pressed against the aorta to allow the blade to cutthrough the wall of the aorta and then repositions to prevent the bladefrom cutting. Other embodiments further include an occluder aligner, alumen which can be used to inflate the or deflate the balloon or anaspiration lumen which terminates with the infusion port. For moredetailed descriptions of the construction of a cardioplegia occluder,the reader is referred to Tsugita et. al., U.S. application Ser. No.08/993,202, filed Dec. 18, 1997, incorporated herein by reference.

[0018] The methods of the present invention include administeringcardioplegia to the aorta during cardiac surgery using a occlusioncannula as described above. An incision is made in the aorta, and thedistal end of the cannula is inserted through the incision. The occluderis expanded to occlude the aorta and thereby isolate the ascending aortafrom peripheral circulation without substantial migration of theoccluder within the ascending aorta. Cardioplegia solution may beinfused through the infusion port to arrest the heart. In embodimentsthat include a cutting blade, the step of making the incision in theaorta is performed by the cutting blade. In embodiments that include anaspiration lumen, the method further includes the step of aspiratingcardioplegia and embolic debris from the aorta by applying negativepressure to the aspiration lumen.

BRIEF DESCRIPTION OF THE DRAWINGS

[0019]FIG. 1 depicts an occlusion cannula according to the invention,having an angled distal segment.

DETAILED DESCRIPTION

[0020] Referring more to the figure, FIG. 1 depicts an embodiment of anocclusion cannula having an angled distal segment. Tubular member 1comprises proximal end 2, distal end 3, distal region 10, and lumen 4.Lumen 4 extends from proximal end 2 to perfusion port 5 in the distalregion. Perfusion port 5 may be a cardioplegia port. Distal region 10 iscomposed of a substantially rigid preformed material which resistsbending under the forces encountered under the differential in bloodpressure during cardiopulmonary bypass in the aorta. Region 10 includesthree segments. First segment 11 is angled from the axis of the proximaltubular member. Second segment 12 curves in a direction opposite fromfirst segment 11. Third segment 13 is substantially linear and lies atapproximately a 90-degree angle to the axis of the proximal tubularmember. The curved segment further inhibits migration of the occlusioncannula in the ascending aorta. Balloon occluder 15, which may comprisean elastomeric balloon, is mounted on third segment 13, distal toperfusion port 5. Balloon inflation lumen 16, communicating with balloonoccluder 15, extends proximal from the distal region. The elongatemember may further comprise suture flange 25. Aspiration lumen 22,extending distally and communicating with perfusion port 5, can be usedto aspirate embolic debris and other unwanted material from the aorta.Lumen 21, which extends distally and communicates with port 20, can beused for measuring blood pressure.

[0021] In using the occlusion cannula described above for cannulation ofa patient's blood vessel, the cannula is first inserted into a bloodvessel, which may be an artery such as an aorta. The cannula may beinserted through an incision in open-heart surgeries or through aport-access in minimally invasive surgeries. The cannula may be securedonto the blood vessel by placing sutures between suture flange 25 andthe outer blood vessel wall. During coronary artery bypass or heartvalve repair surgery, for example, balloon occluder 15 is inflatedthrough inflation lumen 16 to provide isolation of coronary circulationfrom the peripheral circulation for cardiopulmonary bypass. Cardioplegiasolution can then be infused through lumen 4 and port 5 upstream theascending aorta to arrest the heart. During cardiopulmonary bypass, thedifferential pressure gradient across the cannula tends to cause atraditional cannula to migrate upstream the ascending aorta. The curveddistal segment of this occlusion cannula is better adapted to withstandthe higher pressure downstream the aorta, thereby minimizing migrationof the cannula. Blood pressure upstream the aorta may be monitored by ablood pressure monitoring device through port 20 and lumen 21. Embolicmaterials, such as calcium, tissue debris, atheromatous plague, and airmay be aspirated through port 5 and lumen 22.

[0022] The length of an occlusion cannula will generally be between 5and 15 inches, preferably approximately 8 inches. The length of thefirst segment in the distal region will generally be between 0.1 and 0.8inches, preferably approximately 0.3 inches. The length of the segmentin the distal region will generally be between 0.1 and 0.5 inches,preferably approximately 0.2 inches. The length of the third segment inthe distal region will generally be between 0.2 and 0.8 inches,preferably approximately 0.4 inches. The outer diameter of an occlusioncannula lumen will generally be between 0.02 and 0.2 inches, preferablyapproximately 0.1 inches.

[0023] The foregoing ranges are set forth solely for the purpose ofillustrating typical device dimensions. The actual dimensions of adevice constructed according to the principles of the present inventionmay obviously vary outside of the listed ranges without departing fromthose basic principles.

[0024] Although the foregoing invention has, for purposes of clarity ofunderstanding, been described in some detail by way of illustration andexample, it will be obvious that certain changes and modifications maybe practiced which will still fall within the scope of the appendedclaims.

What is claimed is:
 1. A cannula comprising an elongate tubular memberhaving a proximal end, a distal region, a distal end, and a lumenextending from the proximal end to a perfusion port in the distalregion, the distal region having a first segment curved from an axis ofthe proximal tubular member, a second segment that curves in a directionopposite from the first segment, and a third segment that issubstantially linear and lies at approximately a 90-degree angle to theaxis of the proximal tubular member.
 2. The cannula of claim 1 , whereinthe perfusion port is at a junction between the first segment and thesecond segment of the distal region.
 3. The cannula of claim 1 , whereinthe tubular member further comprises a second lumen which extendsdistally and communicates with a second port in the distal region. 4.The cannula of claim 3 , wherein the second port is for measuring bloodpressure.
 5. The cannula of claim 1 , further comprising a suture flangemounted on the tubular member.
 6. The cannula of claim 1 , wherein thetubular member further comprises an aspiration lumen that extendsdistally and communicates with the perfusion port.
 7. The cannula ofclaim 1 , wherein the occluder comprises an elastomeric material.
 8. Thecannula of claim 1 , wherein the perfusion port is a cardioplegia port.9. The cannula of claim 1 , wherein the elongate tubular member is arigid, preformed elongate tubular member.
 10. A method of cannulation ofa patient's blood vessel, comprising the steps of: providing a cannulacomprising an elongate tubular member having a proximal end, a distalregion, and a distal end, the distal region having a first segmentcurved from the axis of the proximal tubular member, a second segmentthat curves in a direction opposite from the first segment, and a thirdsegment that is substantially linear and lies at approximately a 90degree angle to the axis of the proximal tubular member; and insertingthe occlusion cannula into a blood vessel.
 11. The method of claim 10 ,wherein the blood vessel is an artery.
 12. The method of claim 11 ,wherein the artery is the aorta.
 13. The method of claim 10 , furthercomprising the step of connecting the proximal end of the cannula to abypass-oxygenator machine.
 14. The method of claim 10 , wherein thetubular member further comprises an aspiration lumen that extendsdistally and communicates with the perfusion port.
 15. The method ofclaim 14 , further comprising the step of aspirating any one of fluid,blood, emboli, tissue debris, and air through the perfusion port. 16.The method of claim 13 , further comprising the step of performingcardiopulmonary bypass.
 17. The method of claim 10 , further comprisingthe step of performing coronary artery bypass graft surgery.
 18. Themethod of claim 10 , further comprising the step of performing valverepair surgery.
 19. The method of claim 10 , wherein the elongatetubular member is a rigid, preformed elongate tubular member.
 20. Themethod of claim 10 , wherein the elongate tubular member furthercomprises a lumen extending from the proximal end to a perfusion port inthe distal region.